1. Field of the Invention
Methods and apparatus for drying articles, as water soaked books, bread for poultry stuffing, precooked french fried frozen convenience potatoes, wet clay, etc., in a microwave oven are described.
2. Description of Prior Art
Microwave ovens for heating, cooking and drying are daily becoming more popular. Microwave radiation can, instantaneously, deep heat a microwave-lossy, microwave-permeable article where, in contrast, infrared radiation surface heats. Microwave deep heating can result in an article's core heating faster than said article's surface. Since microwave ovens operate with cold walls, the surface of an article loses heat to said cool oven walls and to cool, oven circulating air while its core's heat builds up. In drying, core heating results in an internal vapor pressure build up within said core. This core vapor pressure mechanically drives loose water before it to the surface of the article until at the surface of said article said vapor's pressure releases and said vapor forms a vapor blanket over said surface. In prior art, to speed drying, fans are employed to mechanically break up said vapor blanket and evaporate mechanically released water.
Methods and apparatus for dealing with by-product water and recycling the latent heat of vaporization are described in my U.S. Pat. Nos. 3,985,990 and 3,985,991. This invention does not require a microwave-reflective, heat-conductive container or the microwave lossy auxillary heating elements of my previous inventions, but concerns apparatus and methods designed to take advantage of microwave engendered core heating.